The big Mozilla Persona News is that
Persona now has a gateway for Gmail
users.
If you have GMail and use Persona to sign in to a site,
then Google can see that you're using the gateway, but
not which site you're connecting to.

Privacy
win.
With BrowserID, by design, your identity providers
are not involved in the login transaction. This means
they need not be aware of your entire Web activity,
a significant privacy advantage. With OpenID, your
identity provider is, unfortunately, a necessary
participant in the login flow.

If your email address is on a domain that doesn't have
a gateway or full Persona support, you can still use
Persona, just with an extra step of filling out a form
and getting an email confirmation. Try
it.

Now for the fun part. If you're interested in
adding first-class Persona Identity Provider
support to your own site, so that people who
have an email adddres on your domain can use
it to log in at other places, read one webmaster's
experience.
After a few days of hacking, "rfk.id.au" now acts
as an Identity Provider for the BrowserID protocol,
a.k.a Mozilla Persona. This means I can now log in as
ryan@rfk.id.au on any persona-enabled website while
retaining complete control over my identity. I do
not have to delegate my details or my credentials to
a third party, even one that I would trust as much
as Mozilla.